Virtually all municipal roadway milling and resurfacing projects have to address the presence of multiple manholes. After milling and before paving, manholes are often left raised about 2 in. above the milled surface. During this time, while drivers use the roadway mid-project, the sharp raised manhole rims can cause significant damage to the tires, rims and undercarriages of passenger cars and even construction vehicles. If motorcycles or bicycles hit these raised manholes at normal speeds, serious injuries can occur.
MSR White Paper.pdf